diff --git a/doc/conf.py b/doc/conf.py
index 35ae38bfd..edf5f5459 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -103,7 +103,7 @@
 # built documents.
 #
 # The short X.Y version.
-__version__ = '0.3.0'
+__version__ = '0.4.0.dev0'
 version = __version__
 # The full version, including alpha/beta/rc tags.
 release = __version__
diff --git a/imblearn/version.py b/imblearn/version.py
index 85a931135..ea82ed81e 100644
--- a/imblearn/version.py
+++ b/imblearn/version.py
@@ -21,7 +21,7 @@
 # Dev branch marker is: 'X.Y.dev' or 'X.Y.devN' where N is an integer.
 # 'X.Y.dev0' is the canonical version of 'X.Y.dev'
 #
-__version__ = '0.3.0'
+__version__ = '0.4.0.dev0'
 
 _IMBALANCED_DATASET_INSTALL_MSG = 'See %s for installation information.' % (
     'http://contrib.scikit-learn.org/imbalanced-learn/install.html')
diff --git a/setup.cfg b/setup.cfg
index adfa31708..56cfb932a 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,5 +1,5 @@
 [bumpversion]
-current_version = 0.3.0
+current_version = 0.4.0.dev0
 tag = False
 parse = (?P<major>\d+)\.(?P<minor>\d+)\.(?P<patch>\d+)(\.(?P<release>[a-z]+)(?P<dev>\d+))?
 serialize =